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ABSTRACT: Background/Aims: The association between postoperative infection and prolonged survival in high-grade glioma is still a matter of debate. Previously we demonstrated that the intracerebral (i.c.) injection of heat-inactivated staphylococcal epitopes (HISE) resulted in a well-defined infux of immunocompetent cells across the blood-brain barrier. The present study investigated the potential antitumoral effect of HISE-immunostimulation in an experimental glioma model. Methods: Wistar rats were intracerebrally implanted with 9L gliosarcoma cells (n=6), 9L cells mixed with HISE (n=12), or phosphate buffered saline (n=4). Tumor growth was measured by serial magnetic resonance imaging (MRI). After death due to the tumor burden, the brains were histopathologically assessed for inflammation and oncolysis. A toxicity assay was performed to quantify potential impairment of HISE on tumor cell growth in vitro. Results: Animals treated by HISE showed a significant increase in average survival and even complete regression of an already established mass in one case. Naïve 9L gliosarcomas failed to recruit significant numbers of systemic immune cells. In contrast, concomitant intracerebral HISE inoculation lead to a oncolysis and a distinct peri- and intratumoral infiltration of macrophages, CD8 and CD4 co-expressing T-lymphocytes in two thirds of the tumor-bearing animals. The toxicity screening showed HISE-mediated oncolysis to be ineffective ex vivo. Conclusion: This study describes a novel approach for combatting malignant glioma using inactivated staphylococci as potent immunomodulators. Our results provide an outline for investigating the strategic potential of bacteria as emerging future therapeutics.
Cellular Physiology and Biochemistry 05/2013; 31(4-5):614-624. · 2.86 Impact Factor
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ABSTRACT: AIMS: Currently available animal models incompletely capture the complex pathophysiology of Alzheimer's disease (AD), typically involving β-amyloidosis, neurofibrillary tangle formation and loss of basal forebrain cholinergic projection neurons (CPN). While age-dependent β-amyloidosis and tau hyperphosphorylation are mimicked in triple-transgenic mice (3xTg), experimental induction of CPN loss in these mice is still lacking. Here, we introduce a more-complex animal model of AD by inducing cellular loss of CPN in an already existing transgenic background aiming to elucidate subsequent changes of hippocampal β-amyloid (Aβ) and tau pathology. METHODS: Twelve-month-old 3xTg mice intracerebroventricularly received the rabbit-anti-low affinity neurotrophin receptor p75-saporin, an immunotoxin specifically targeting forebrain CPN. After histochemical verification of immunolesion in immersion-fixed forebrains, markers of Aβ and tau metabolism were analysed using quantitative Western blot analyses of hippocampi from these mice. In parallel, these markers and glial activation were investigated by multiple immunofluorescence labelling of perfusion-fixed hippocampi and confocal laser-scanning microscopy. RESULTS: Four months after immunolesion, the selective lesion of CPN was verified by disappearance of choline acetyltransferase and p75 immunolabelling. Biochemical analysis of hippocampi from immunolesioned mice revealed enhanced levels of Aβ, amyloid precursor protein (APP) and its fragment C99. Furthermore, immunolesion-induced increase in levels of phospho-tau and tau with AD-like conformation were seen in 16-month-old mice. Immunofluorescence staining confirmed an age-dependent occurrence of hippocampal Aβ-deposits and phospho-tau, and demonstrated drastic gliosis around Aβ-plaques after immunolesion. CONCLUSION: Overall, this extended model promises further insights into the complexity of AD and contributes to novel treatment strategies also targeting the cholinergic system.
Neuropathology and Applied Neurobiology 04/2013; · 3.80 Impact Factor
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ABSTRACT: N-terminally truncated pyroglutamate amyloid-β (Aβ) starting at position 3 (AβpE3) represents a major fraction of Aβ peptides in Alzheimer's disease (AD). Recently, we have identified low molecular weight AβpE3 oligomers, which can be detected by 9D5, a novel mouse monoclonal antibody. In the present study, we analyzed the immunohistochemical staining profile in the brain of patients with AD and in the APP/PS1KI mouse model, as well as in aged rhesus monkeys. 9D5-positive microglia and blood vessels were found in many AD cases, in the transgenic mouse model, and in an aged macaque. The presence of 9D5-immunoreactivity in microglia indicates that low molecular weight AβpE3 oligomers may be phagocytosed, since in the APP/PS1KI model, Aβ is exclusively produced in neurons due to neuronal expression of transgenic AβPP.
Journal of Alzheimer's disease: JAD 03/2013; · 3.74 Impact Factor
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ABSTRACT: The term blood-brain barrier (BBB) relates to the ability of cerebral vessels to hold back hydrophilic and large molecules from entering the brain, thereby crucially contributing to brain homeostasis. In fact, experimental opening of endothelial tight junctions causes a breakdown of the BBB evidenced as for instance by albumin leakage. This and similar observations led to the conclusion that BBB breakdown is predominantly mediated by damage to tight junction complexes, but evidentiary ultrastructural data are rare. Since functional deficits of the BBB contribute to an increased risk of hemorrhagic transformation and brain edema after stroke, which both critically impact on the clinical outcome, we studied the mechanism of BBB breakdown using an embolic model of focal cerebral ischemia in Wistar rats to closely mimic the essential human pathophysiology. Ischemia-induced BBB breakdown was detected using intravenous injection of FITC-albumin and tight junctions in areas of FITC-albumin extravasation were subsequently studied using fluorescence and electron microscopy. Against our expectation, 25 hours after ischemia induction the morphology of tight junction complexes (identified ultrastructurally and using antibodies against the transcellular proteins occludin and claudin-5) appeared to be regularly maintained in regions where FITC-albumin massively leaked into the neuropil. Furthermore, occludin signals along pan-laminin-labeled vessels in the affected hemisphere equaled the non-affected contralateral side (ratio: 0.966 0.963; P = 0.500). Additional ultrastructural analyses at 5 and 25 h after ischemia induction clearly indicated FITC-albumin extravasation around vessels with intact tight junctions, while the endothelium exhibited enhanced transendothelial vesicle trafficking and signs of degeneration. Thus, BBB breakdown and leakage of FITC-albumin cannot be correlated with staining patterns for common tight junction proteins alone. Understanding the mechanisms causing functional endothelial alterations and endothelial damage is likely to provide novel protective targets in stroke.
PLoS ONE 01/2013; 8(2):e56419. · 4.09 Impact Factor
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ABSTRACT: The inflammatory response following traumatic brain injury (TBI) contributes to neuronal death with poor outcome. Although anti-inflammatory strategies were beneficial in experimental TBI, clinical translations mostly failed, probably caused by the complexity of involved cells and mediators. We recently showed in a rat model of controlled cortical impact (CCI) that leukotriene inhibitors (LIs) attenuate contusion growth and improve neuronal survival. This study focuses on spatiotemporal characteristics of macrophages and granulocytes, typically involved in inflammatory processes, and neuronal COX-2 expression. Effects of treatment with LIs (Boscari/MK-886), started prior trauma, were evaluated by quantifying CD68(+), CD43(+) and COX-2(+) cells 24h and 72h post-CCI in the parietal cortex (PC), CA3 region, dentate gyrus (DG) and visual/auditory cortex (v/aC). Correlations were applied to identify inter-cellular relationships. At 24h, untreated animals showed granulocyte invasion in all regions, decreasing towards 72h. Macrophages increased from 24h to 72h post-CCI in PC and v/aC. COX-2(+) neurones showed no temporal changes, except of an increase in the CA3 region at 72h. Treatment reduced granulocytes at 24h in the pericontusional zone and hippocampus, and macrophages at 72h in the PC and v/aC. COX-2 expression remained unaffected by LIs, except of time-specific changes in the DG (increase/decrease at 24/72h). Interrelations confirmed concomitant cellular reactions beyond the initial trauma site. In conclusion, LIs attenuated the cellular inflammatory response following CCI. Future studies have to clarify region-specific effects and explore the potential of a clinically more relevant therapeutic approach applying LIs after CCI.
Brain research 12/2012; · 2.46 Impact Factor
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ABSTRACT: There is accumulating evidence that glutamate and gamma-aminobutyric acid (GABA) release are key mechanisms of ischaemic events in the central nervous system (CNS). However, data on the expression of involved transporters for these mediators are inconsistent, potentially impeding further neuroprotective approaches. Here, we applied immunofluorescence labelling to characterise the expression pattern of vesicular glutamate (VGLUT) and GABA transporters (VGAT) after acute focal cerebral ischaemia and in two models of retinal ischaemia. Mice were subjected to filament-based focal cerebral ischaemia predominantly involving the middle cerebral artery territory, also leading to retinal ischaemia due to central retinal artery occlusion (CRAO). Alternatively, retinal ischaemia was induced by a transient increase of intraocular pressure (HIOP). One day after ischaemia onset, diminished immunolabelling of neuronal nuclei and microtubule-associated protein 2-positive structures were found in the ipsilateral neocortex, subcortex and the retina, indicating neuronal degeneration. VGLUT1 expression did not change significantly in ischaemic tissues whereas VGLUT2 was down-regulated in specific areas of the brain. VGLUT3 expression was only slightly down-regulated in the ischaemia-affected neocortex, and was found to form clusters on fibrils of unknown origin in the ischaemic lateral hypothalamus. In contrast, retinae subjected to CRAO or HIOP displayed a rapid loss of VGLUT3-immunoreactivity. The expression of VGAT appears resistant to ischaemia as there was no significant alteration in all regions analysed. In summary, these data indicate a region- and subtype-specific change of VGLUT expression in the ischaemia-affected CNS, whose consideration might help to generate specific neuroprotective strategies.
Neuroscience 12/2012; · 3.38 Impact Factor
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ABSTRACT: Since several neuroprotectives failed to reproduce promising preclinical results under clinical conditions, efforts emerged to implement clinically relevant endpoints in animal stroke studies. Thereby, insufficient attention was given on autonomic reactions due to experimental stroke, although clinical trials reported on high functional and prognostic impact. This study focused on autonomic consequences and body weight changes in a translational relevant stroke model and investigated interrelations to different outcome measurements.
Forty-eight rats underwent thromboembolic middle cerebral artery occlusion (MCAO) while recording heart rate (HR) and mean arterial pressure (MAP). After assessing early functional impairment (Menzies score), animals were assigned to control procedure or potentially neuroprotective treatment with normobaric (NBO) or hyperbaric oxygen (HBO). Four or 24 hours after ischemia onset, functional impairment was re-assessed and FITC-albumin administered intravenously obtaining leakage-related blood-brain barrier (BBB) impairment. Body weight was documented prior to MCAO and 4 or 24 hours after ischemia onset.
During MCAO, HR was found to increase significantly while MAP decreased. The amount of changes in HR was positively correlated with early functional impairment (P = 0.001): Severely affected animals provided an increase of 15.2 compared to 0.8 beats/minute in rats with low impairment (P = 0.048). Regarding body weight, a decrease of 9.4% within 24 hours after MCAO occurred, but treatment-specific alterations showed no significant correlations with respective functional or BBB impairment.
Future studies should routinely include autonomic parameters to allow inter-group comparisons and better understanding of autonomic reactions due to experimental stroke. Prospectively, autonomic consequences might represent a useful outcome parameter enhancing the methodological spectrum of preclinical stroke studies.
Experimental and Translational Stroke Medicine 04/2012; 4(1):7.
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ABSTRACT: CT and MR imaging techniques are frequently used for the diagnosis and progress monitoring of ischemic stroke in clinical practice and research. After stroke, both methods are characterized by a transient pseudo-normalized imaging signal, the so-called fogging phenomenon. This study evaluates potential pathophysiological changes associated with fogging, as well as its influence on the correct determination of the ischemic lesion in a rat stroke model.
Male spontaneously hypertensive rats were subjected to permanent middle cerebral artery occlusion. Ischemic lesion volume, brain edema and gray scale value spread within the ischemic lesion were determined on T2-weighted MR sequences at days 1, 4, 8, 11 and 29 after stroke onset, and compared with immunohistochemistry for astrogliosis, microglia/macrophage infiltration and angiogenesis.
All animals showed MR fogging at days 4, 8 and 11 after stroke. The transient normalization of T2 signals occurred independently from the development of infarct volumes, but coincided well with the spatio-temporal occurrence of necrosis, angiogenesis and microglia/macrophage infiltration.
Our results suggest that the fogging effect reflects the clearance of necrotic tissue within the ischemic lesion and is thus not relevant for the determination of the lesion volume.
NeuroImage 04/2012; 61(4):780-5. · 5.89 Impact Factor
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Flavia Antonucci,
Alán Alpár,
Johannes Kacza,
Matteo Caleo,
Claudia Verderio,
Alice Giani,
Henrik Martens,
Farrukh A Chaudhry,
Manuela Allegra,
Jens Grosche,
Dominik Michalski,
Christian Erck,
Anke Hoffmann,
Tibor Harkany,
Michela Matteoli, Wolfgang Härtig
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ABSTRACT: Inhibitory (GABAergic) interneurons entrain assemblies of excitatory principal neurons to orchestrate information processing in the hippocampus. Disrupting the dynamic recruitment as well as the temporally precise activity of interneurons in hippocampal circuitries can manifest in epileptiform seizures, and impact specific behavioral traits. Despite the importance of GABAergic interneurons during information encoding in the brain, experimental tools to selectively manipulate GABAergic neurotransmission are limited. Here, we report the selective elimination of GABAergic interneurons by a ribosome inactivation approach through delivery of saporin-conjugated anti-vesicular GABA transporter antibodies (SAVAs) in vitro as well as in the mouse and rat hippocampus in vivo. We demonstrate the selective loss of GABAergic--but not glutamatergic--synapses, reduced GABA release, and a shift in excitation/inhibition balance in mixed cultures of hippocampal neurons exposed to SAVAs. We also show the focal and indiscriminate loss of calbindin(+), calretinin(+), parvalbumin/system A transporter 1(+), somatostatin(+), vesicular glutamate transporter 3 (VGLUT3)/cholecystokinin/CB(1) cannabinoid receptor(+) and neuropeptide Y(+) local-circuit interneurons upon SAVA microlesions to the CA1 subfield of the rodent hippocampus, with interneuron debris phagocytosed by infiltrating microglia. SAVA microlesions did not affect VGLUT1(+) excitatory afferents. Yet SAVA-induced rearrangement of the hippocampal circuitry triggered network hyperexcitability associated with the progressive loss of CA1 pyramidal cells and the dispersion of dentate granule cells. Overall, our data identify SAVAs as an effective tool to eliminate GABAergic neurons from neuronal circuits underpinning high-order behaviors and cognition, and whose manipulation can recapitulate pathogenic cascades of epilepsy and other neuropsychiatric illnesses.
Journal of Neuroscience 02/2012; 32(6):1989-2001. · 7.11 Impact Factor
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ABSTRACT: Recent evidence suggests that soluble oligomeric amyloid-β (Aβ) assemblies are critically involved in the pathogenesis of Alzheimer's disease (AD). We have generated a conformation-dependent monoclonal antibody (9D5) that selectively recognizes low-molecular weight AβpE3 oligomers, and demonstrated its diagnostic and therapeutic potential. Here, we further characterize the specificity of this antibody by evaluating a spectrum of neurodegeneration-related protein deposits for cross-reactivity, and by comparing the staining pattern of 9D5 with a generic Aβ antibody that targets a linear epitope (mAb NT244), and with another conformation-dependent Aβ antibody that selectively labels amyloid fibrils of various molecular weights (pAb OC). The 9D5 antibody does not cross-react with other aggregated protein deposits in brains of progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease, Pick's disease, Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, frontotemporal lobar degeneration or amyotrophic lateral sclerosis with TDP-43 inclusions, Creutzfeldt-Jakob disease, and vessel changes in Binswanger encephalopathy, demonstrating the specificity of 9D5 for Aβ deposits. While NT244 and OC showed a comparable plaque load, 9D5 detected only approximately 15% of the total Aβ plaque load in the entorhinal cortex, the CA1 region, and the temporal neocortex. Our study further supports a possible therapeutic advantage of 9D5 by the highly specific recognition of an epitope found only in oligomeric assemblies of AβpE3 of AD patients. Moreover, selective binding to only a pathogenetically relevant fraction of Aβ deposits serves as rationale for passive immunization with 9D5-derivatives by limiting potential side effects of vaccination due to dissolvement of existing amyloid deposits.
Journal of Alzheimer's disease: JAD 01/2012; 29(2):361-71. · 3.74 Impact Factor
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ABSTRACT: Human fetal midbrain-derived neural progenitor cells (NPCs) may deliver a tissue source for drug screening and regenerative cell therapy to treat Parkinson's disease. While glutamate and GABA(A) receptors play an important role in neurogenesis, the involvement of glycine receptors during human neurogenesis and dopaminergic differentiation as well as their molecular and functional characteristics in NPCs are largely unknown.
Here we investigated NPCs in respect to their glycine receptor function and subunit expression using electrophysiology, calcium imaging, immunocytochemistry, and quantitative real-time PCR. Whole-cell recordings demonstrate the ability of NPCs to express functional strychnine-sensitive glycine receptors after differentiation for 3 weeks in vitro. Pharmacological and molecular analyses indicate a predominance of glycine receptor heteromers containing α2β subunits. Intracellular calcium measurements of differentiated NPCs suggest that glycine evokes depolarisations mediated by strychnine-sensitive glycine receptors and not by D-serine-sensitive excitatory glycine receptors. Culturing NPCs with additional glycine, the glycine-receptor antagonist strychnine, or the Na(+)-K(+)-Cl(-) co-transporter 1 (NKCC1)-inhibitor bumetanide did not significantly influence cell proliferation and differentiation in vitro.
These data indicate that NPCs derived from human fetal midbrain tissue acquire essential glycine receptor properties during neuronal maturation. However, glycine receptors seem to have a limited functional impact on neurogenesis and dopaminergic differentiation of NPCs in vitro.
PLoS ONE 01/2012; 7(5):e36946. · 4.09 Impact Factor
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ABSTRACT: In ischemic stroke, blood-brain barrier (BBB) regulations, typically involving matrix metalloproteinases (MMPs) and inhibitors (TIMPs) as mediators, became interesting since tissue plasminogen activator (tPA)-related BBB breakdown with risk of secondary hemorrhage was considered to involve these mediators too. Despite high clinical relevance, detailed interactions are purely understood. After a pilot study addressing hyperoxia as potential neuroprotective co-treatment to tPA, we analyzed interrelations between BBB permeability (BBB-P), MMPs and TIMPs.
Rats underwent embolic middle cerebral artery occlusion (eMCAO) and treatment with normobaric (NBO) or hyperbaric oxygen (HBO), tPA, tPA+HBO, or no treatment. BBB-P was assessed by intravenously applied FITC-albumin at 4 or 24 hours. MMP-2/-9 and TIMP-1/-2 serum levels were determined at 5 or 25 hours. Time point-corrected partial correlations were used to explore interrelations of BBB-P in ischemic regions (extra-/intravasal FITC-albumin ratio) and related serum markers. BBB-P correlated positively with MMP-2 and MMP-9 in controls, whereas hyperoxia led to an inverse association, most pronounced for HBO/MMP-9 (r = -0.606; P < 0.05). As expected, positive coefficients were observed after treatment with tPA. Co-treatment with HBO attenuated and in part reversed this effect, but to a lower degree than HBO alone. Amongst MMPs and TIMPs, significant associations shifted from MMP-9 to -2 when comparing treatment with HBO/tPA and tPA+HBO. TIMPs were significantly interrelated after tPA, tPA+HBO, and interestingly, HBO alone.
HBO was found to reverse the positively directed interrelation of BBB-P and MMPs after eMCAO, but this effect failed to sustain in the expected amount when HBO and tPA were given simultaneously.
Medical gas research. 01/2012; 2(1):2.
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ABSTRACT: Cortical and subcortical inputs to the striatum are functionally highly organized and they obey to some extent striatal patch-matrix topography. Whether this organization is reflected in the density of various glutamatergic endings is unknown. We therefore mapped boutons expressing the vesicular glutamate transporters VGluT1 and VGluT2, together with boutons immunoreactive for vesicular γ-aminobutyric acid (GABA) transporter (VGAT) in patch and matrix throughout the striatum. We used triple-immunofluorescence staining followed by multichannel, high-magnification confocal laser scanning and 3D object recognition. Densities of VGluT1 and VGluT2 boutons were on average higher in matrix than in patches in all striatal sectors. The dorsal one-third of the striatum contained the highest densities of VGluT1 boutons. Subsequent 3D surface plotting revealed patterns of density "valleys" in the dorsomedial striatum coinciding with patch locations in the patch-matrix mapping. The density of VGluT1 boutons increased along three axes: ventrolateral-to-dorsomedial, ventral-to-dorsal, and lateral-to-medial. In contrast, VGluT2 showed a global increase in density from lateral to medial and a relatively high density in the ventral striatum. VGAT appeared more evenly distributed in the striatal patch-matrix than the VGluTs, with a tendency of bouton density to increase from medial to lateral. We noted a good correlation between the high VGluT1 bouton density dorsomedially with inputs from dorsal medial prefrontal cortex and related thalamic regions, and the enhanced VGluT2 input ventromedially with input from ventral medial prefrontal cortex and thalamic, amygdaloid, and hippocampal sources.
The Journal of Comparative Neurology 12/2011; 520(10):2123-42. · 3.81 Impact Factor
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ABSTRACT: The occurrence of orthosteric and allosteric binding sites is a characteristic common feature of several acetylcholine- binding proteins, like acetylcholinesterase or the nicotinic and muscarinic acetylcholine receptors. These proteins are involved in a number of neurological disorders, such as Alzheimer's disease, and represent important therapeutic targets for the development of heterodimeric ligands addressing both of their binding sites. Among the pharmacophores, which have been combined in such heterodimers, the tetrahydroacridine derivative tacrine has attracted particular interest. This review discusses the chemistry behind the linker connection of tacrine to other pharmacophores and summarizes the types of linkers established to date. Especially, the development of a hydrazide linker for tacrine-derived heterodimers is highlighted by applications in the inhibition of cholinesterases, the bivalent binding to nicotinic and muscarinic acetylcholine receptors, as well as the histochemical imaging of acetylcholinesterase and amyloid-β.
Current topics in medicinal chemistry 11/2011; 11(22):2731-48. · 4.47 Impact Factor
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ABSTRACT: Acute focal cerebral ischemia and consecutive energy failure are accompanied by neuronal death in regions with impaired cerebral blood flow. Several translational attempts of potential neuroprotective agents have failed, hence extended perspectives are required regarding the regional differences of neuronal impairment and glial involvement by using clinically relevant stroke models. This study aimed on neuronal loss following experimental focal cerebral ischemia, considering tissue plasminogen activator (tPA) as established treatment in stroke and hyperbaric oxygenation (HBO) as potential neuroprotective co-treatment. Wistar rats were subjected to embolic middle cerebral artery occlusion and underwent either treatment with tPA only, combined tPA+HBO, or no treatment. Neuronal impairment was assessed by Neuronal Nuclei (NeuN) staining in 4 ischemia-related areas and at 4 different time points after stroke induction (24hours, 7, 14 and 28 days). Additionally, spatial relationships between neuronal loss and gliosis were revealed by triple fluorescence staining of neurons, astrocytes and microglia, comparing the ipsi- and contra-lesional hemisphere. Analyzing the ischemic injury in general, a shell-like distribution of neuronal damage was observed, starting in the ischemic core and diminishing over the general ischemic area to the ischemic border zone and the primary non-affected area. This pattern remained detectable up to 4weeks after ischemia induction. Surprisingly, tPA and tPA+HBO did not markedly affect the post-ischemic course of neuronal impairment. Further studies are needed to investigate the effects of treatment with tPA or potential neuroprotective agents on neuronal integrity, with emphasis on the separation of intact neurons from those undergoing apoptosis or necrosis.
Brain research 08/2011; 1417:115-26. · 2.46 Impact Factor
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ABSTRACT: After promising results in experimental stroke, normobaric (NBO) or hyperbaric oxygenation (HBO) have recently been discussed as co-medication with tissue plasminogen activator (tPA) for improving outcome. This study assessed the interactions of hyperoxia and tPA, focusing on survival, early functional outcome and blood-brain barrier (BBB) integrity following experimental stroke.
Rats (n = 109) underwent embolic middle cerebral artery occlusion or sham surgery. Animals were assigned to: Control, NBO (60-minute pure oxygen), HBO (60-minute pure oxygen at 2.4 absolute atmospheres), tPA, or HBO+tPA. Functional impairment was assessed at 4 and 24 hours using Menzies score, followed by intravenous application of FITC-albumin as a BBB permeability marker, which was allowed to circulate for 1 hour. Further, blood sampling was performed at 5 and 25 hours for MMP-2, MMP-9, TIMP-1 and TIMP-2 concentration.
Mortality rates did not differ significantly between groups, whereas functional improvement was found for NBO, tPA and HBO+tPA. NBO and HBO tended to stabilize BBB and to reduce MMP-2. tPA tended to increase BBB permeability with corresponding MMP and TIMP elevation. Co-administered HBO failed to attenuate these early deleterious effects, independent of functional improvement.
The long-term consequences of simultaneously applied tPA and both NBO and HBO need to be addressed by further studies to identify therapeutic potencies in acute stroke, and to avoid unfavorable courses following combined treatment.
Experimental and Translational Stroke Medicine 06/2011; 3(1):5.
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ABSTRACT: Previous RT-PCR experiments revealed that the neural retina of the rat contains gene transcripts of numerous aquaporins (AQPs), including AQP6 (Tenckhoff et al., Neuroreport 16 (2005) 53-56). In the present study, we investigated the localization of AQP6 immunoreactivity in slices of the rat neural retina, and determined whether blue light injury of the retina affects the tissue distribution of this channel. AQP6 immunoreactivity was found to be selectively localized to the outer plexiform layer. Around the ribbon synapses in this layer, AQP6 labeling was co-localized with the glial water channel AQP4. AQP6 labeling was not colocalized with the marker of horizontal cells, calbindin, nor with the marker of rod bipolar cells, protein kinase Cα. Along with the degeneration of photoreceptor cells after blue light treatment of the retina, AQP6-labeled ribbon synapses disappeared, and a punctate AQP6 staining redistributed into the inner nuclear layer. The co-localization of AQP6 and the glial water channel AQP4 suggests a preferential localization of AQP6 in glial membranes that surround the ribbon synapses in the outer plexiform layer. AQP6 might be involved in the glia-mediated osmo and ion regulation of the extracellular space in this layer.
Neuroscience Letters 02/2011; 490(2):130-4. · 2.11 Impact Factor
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ABSTRACT: The deposition of amyloid-β (Aβ) peptides in the walls of leptomeningeal and cortical blood vessels as cerebral amyloid angiopathy (CAA) is present in normal ageing and the majority of Alzheimer's disease (AD) brains. The failure of clearance mechanisms to eliminate Aβ from the brain contributes to the development of sporadic CAA and AD. Here, we investigated the effects of CAA and ageing on the pattern of perivascular drainage of solutes in the brains of naïve mice and in the Tg2576 mouse model of AD. We report that drainage of small molecular weight dextran along cerebrovascular basement membranes is impaired in the hippocampal capillaries and arteries of 22-month-old wild-type mice compared to 3- and 7-month-old animals, which was associated with age-dependent changes in capillary density. Age-related alterations in the levels of laminin, fibronectin and perlecan in vascular basement membranes were also noted in wild-type mice. Furthermore, dextran was observed in the walls of veins of Tg2576 mice in the presence of CAA, suggesting that deposition of Aβ in vessel walls disrupts the normal route of elimination of solutes from the brain parenchyma. These data support the hypothesis that perivascular solute drainage from the brain is altered both in the ageing brain and as a consequence of CAA. These findings have implications for the success of therapeutic strategies for the treatment of AD that rely upon the health of the ageing cerebral vasculature.
Acta Neuropathologica 01/2011; 121(4):431-43. · 9.32 Impact Factor
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ABSTRACT: Abnormal phosphorylation and aggregation of tau protein are hallmarks of a variety of neurological disorders, including Alzheimer's disease (AD). Increased tau phosphorylation is assumed to represent an early event in pathogenesis and a pivotal aspect for aggregation and formation of neurofibrillary tangles. However, the regulation of tau phosphorylation in vivo and the causes for its increased stage of phosphorylation in AD are still not well understood, a fact that is primarily based on the lack of adequate animal models. Recently we described the reversible formation of highly phosphorylated tau protein in hibernating European ground squirrels. Hence, mammalian hibernation represents a model system very well suited to study molecular mechanisms of both tau phosphorylation and dephosphorylation under in vivo physiological conditions. Here, we analysed the extent and kinetics of hibernation-state dependent tau phosphorylation in various brain regions of three species of hibernating mammals: arctic ground squirrels, Syrian hamsters and black bears. Overall, tau protein was highly phosphorylated in torpor states and phosphorylation levels decreased after arousal in all species. Differences between brain regions, hibernation-states and phosphosites were observed with respect to degree and kinetics of tau phosphorylation. Furthermore, we tested the phosphate net turnover of tau protein to analyse potential alterations in kinase and/or phosphatase activities during hibernation. Our results demonstrate that the hibernation-state dependent phosphorylation of tau protein is specifically regulated but involves, in addition, passive, temperature driven regulatory mechanisms. By determining the activity-state profile for key enzymes of tau phosphorylation we could identify kinases potentially involved in the differentially regulated, reversible tau phosphorylation that occurs during hibernation. We show that in black bears hibernation is associated with conformational changes of highly phosphorylated tau protein that are typically related to neuropathological alterations. The particular hibernation characteristics of black bears with a continuous torpor period and an only slightly decreased body temperature, therefore, potentially reflects the limitations of this adaptive reaction pattern and, thus, might indicate a transitional state of a physiological process.
PLoS ONE 01/2011; 6(1):e14530. · 4.09 Impact Factor
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ABSTRACT: Cleaved caspase-3 (CC3) is well known as an executioner protease of apoptosis following brain ischemia. However, an increasing body of evidence suggests several non-apoptotic functions of CC3. To improve our understanding of the relation between cell death-related and non-adverse effects of postischemic caspase-3 activation, we examined the spatiotemporal distribution and identity of CC3-positive cells at days 2, 3 and 4 after permanent middle cerebral artery occlusion in rats. The lacking colocalization of CC3 and TUNEL staining indicated, that CC3 expression was predominantly non-apoptotic. Nuclear CC3 expression was frequently found to be colocalized with GFAP-positive astrocytes within the tissue adjacent to the infarct, whereas cytoplasmatic CC3 expression occurred solely in the lesion. Multiple fluorescence labeling revealed costaining of cytoplasmatic CC3 with markers directed against astrocytes, macrophages/microglia and supposedly pericytes. Our findings suggest that CC3 expression was predominantly associated with cellular responses to stroke such as reactive astrogliosis and the infiltration of macrophages.
Brain research 01/2011; 1381:237-42. · 2.46 Impact Factor
